An image forming apparatus such as a Multi-functional Peripheral (hereinafter referred to as “MFP”), a printer, and the like typically includes a fixing apparatus. The fixing apparatus of one type causes heat generation for the fixing by an electromagnetic induction heating unit (hereinafter referred to as an “IH” unit). A fixing apparatus that includes the IH unit includes a fixing belt and an auxiliary heating unit that generate heat. The IH unit is usually configured to maintain its output level to maintain a certain amount of heat generation. For example, when the auxiliary heating unit loses its magnetism as the temperature thereof increases too much, electric resistance of the IH unit decreases. In this case, to maintain the output level, level of a current supplied from a driving circuit to the IH unit is increased. However, this increase of the current level may damage the driving circuit.